This study is based on the weekly collection of fishes from commercial bottom trawlers landed at Aryapally and Gopalpur fishing harbour, Ganjam Orissa. A total sample of 405 nos. of mature fishes with a size range between 121– 260 mm in length were collected during August-2017 to July-2018. The length at first maturity (50%) for is 176.5 mm in P. macrophthalmus. The diameter of fully ripe ova was found as 0.76 mm. It was revealed from the qualitative and quantitative gonadal study that for P. macrophthalmus is a asynchronous spawner in October and February to May. Annual male and female sex ratio of population was 1: 1.88 throughout the year. Females dominated males throughout the year except March i.e. after spawning. Seven gonadal development stages were identified. The absolute fecundity ranged from 85,124 - 3,21,564 eggs, with ovary weighing between 3.516 - 19.52 gm. The linear relationship between length and fecundity of was Log F = - 3.9299 + 3.9070 Log L ( r2 = 0.8960) showing good relationship between length and fecundity. it is apparent that in P. macrophthalmus when one batch of mature eggs is about to be shed another batch is getting ready immediately. The results of the study will help in the management options for a sustainable yield future generation

Length at first maturity, asynchronous Fecundity, spawning

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S.K. Bhuyan, B.K. Khuntia, Dipsikha Nayak and Rajashree Jena (2020). Reproductive Biology Study of Big-Head Pennah Croaker (Pennahia macrophthalmus (Bleeker, 1850) from off Ganjam Coast, Odisha, India. Biological Forum – An International Journal, 12(1): 62-66